Transdermal and topical drug delivery can be used for therapeutic treatment, but the number of molecules that can be effectively delivered using these routes can be limited by the barrier properties of skin.
A number of different skin treatment methods have been proposed in order to increase the permeability or porosity of the outermost skin layers, thus enhancing drug delivery through or into those layers. Among these methods are microneedles, laser ablation, RF ablation, heat ablation, sonophoresis, and iontophoresis.
In some cases, these treatments are provided by a single integrated device that performs two separate functions: the device treats the skin and also delivers an active ingredient to the treated skin. An example would be a hollow microneedle array with an attached drug reservoir. The microneedles pierce the skin and remain attached while the drug flows from the reservoir into the skin. Although devices of this type may be conceptually easy for a patient to administer, they can be complex and/or limited in the amount of drug they can effectively deliver.
Alternatively, a treatment device can be used in a first step to perform the function of treating the skin to increase permeability and/or create pores. The treatment device is then removed and, in a second step, a separate drug reservoir (e.g., a cream, solution, or patch) is placed on the treated skin area to perform the second function of delivering the active ingredient to the treated skin. Although this includes an additional user step, the separation of skin treatment from drug delivery can afford simplicity in device design, as well as providing flexibility in the design to better match the specific needs of these two different functions.